Prairie voles are renowned for being faithful mates, but some individuals are more loyal than others. The difference may lie in repetitive genetic sequences often dismissed as so-called junk DNA, according to new research. The longer these sequences, or microsatellites, the more attentive males were to their female partners and their offspring.
In the mid-1990s, researchers discovered a key microsatellite difference between prairie voles and their more promiscuous cousins, the meadow voles. Prairie voles have longer microsatellites near the gene encoding a receptor (V1aR) for the brain chemical vasopressin, and as a result they make more of the receptor than do meadow voles. Last year, Lawrence Young of Emory University in Atlanta, Georgia and colleagues caused meadow voles to emulate the faithful ways of prairie voles by adding extra copies of the V1aR gene to a portion of their brain (Science, 7 January, p. 30).
Now, Young and Elizabeth Hammock of Vanderbilt University in Nashville, Tennessee, have found that variations in V1aR-associated microsatellites among individual prairie voles influence expression of the gene and overall behavior. They paired and bred voles with long microsatellites and found the resulting males spend more time licking and grooming their pups than did males with short microsatellites. They also placed males in cages with a female, allowing 18 hours for them to bond, then added a new female. Males with longer microsatellites spent more time with their partners than did those with shorter microsatellites, the team reports in tomorrow's issue of Science.
Although there's no evidence that human infidelity or poor parenting stems from similar variations, Hammock and Young, as well as other researchers, have begun to explore whether microsatellites can account for behavioral differences between people and primates such as chimps and bonobos. The new study's results "will force us to think about these variations in so-called junk DNA and how [they] make for changes in behavior," says Scott Young (who is not related to Lawrence Young), a neuroscientist at the National Institute of Mental Health in Rockville, Maryland.
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